OVERALL OBJECTIVES OF THE PROJECT: Cataracts occur when intralenticular light scattering increases and the image forming capability of the animal lens decreases. The objectives of this project are (1) the biophysical and biochemical characterization of scattering elements which are the cause of cataracts and (2) the development of chemical methods for improving transparency of cataractous lenses. Chemical agents that produce opacification or restore transparency will be investigated by quasi-elastic laser light scattering spectroscopy, and the studies of light scattering will be correlated with the studies of the biological structure and biochemical composition of animal and human lenses. An understanding of the biophysics and biochemistry of light scattering in the lens may lead to the effective regulation of lens opacification. GOALS FOR THE CURRENT YEAR: (1) Identify the scattering elements for lens opacification; (2) study the biophysical and biochemical control of lens opacification; (3) develop methods for the chemical reversal of lens opacification; (4) describe the biophysical and biochemical properties of lens opacification including the effects of ionic strength, protein composition, temperature, pH and other parameters on lens transparency. RESULTS OF THE PREVIOUS YEAR: A primary goal of our research is the biophysical and biochemical identification of scattering elements responsible for opacification of the animal lens. In these studies, we found that scattering elements could be produced in the lens nucleus or cortex by controlling physical and chemical conditions. Opacification in the calf lens nucleus occurs at a specific cataract temperature, Tc, of 17 degrees C. The Tc is regulated by monovalent cation concentration (delta c/(salt) equals plus 25 degrees C/M) so that nuclear cataracts appear at body temperature (37 degrees C) when a lens is incubated in a solution of 0.6 M saline for 3 hours.